It is known that in a vacuum cleaner the suction force is usually adjusted manually by the user according to the surface that the user intends to clean. This system generally has a potentiometer which allows varying the speed of the motor of the fan of the vacuum cleaner. In these systems, the user must therefore manually vary the working setting of the vacuum cleaner according to the type of surface to be cleaned.
Usually, the user uses the maximum speed of the fan needlessly. In these conditions, besides having a high noise level, the energy consumption is higher than necessary and there is no improvement in the resulting cleaning.
Moreover, when the user leaves the vacuum cleaner in an inactive condition with the motor running, the suction force does not decrease. Accordingly, the fan of the vacuum cleaner continues to rotate at the rate set by the user. This is so also, for example, when the suction hose is not in contact with the surface of the floor to be cleaned. This results, therefore, in the drawbacks that energy consumption is needlessly high and the noise level is highly unpleasant.